1. Field of the Invention
The present invention relates to a slide part in which a hard member is in sliding contact with a seal member formed of an elastic body, and more particularly, to a slide part having an amorphous carbon coating formed on a sliding surface of the hard member and equipment including the invented slide part.
2. Description of Related Art
Slide parts with amorphous carbon coatings formed on their sliding surfaces have been under intense research and development in order primarily to lower friction at sliding points of automobile parts or the like. Thin film materials referred to as a-C (amorphous carbon), a-C:H (hydrogenated amorphous carbon), i-C (i-carbon), DLC (diamond-like carbon), hard carbon, etc. are commonly used for amorphous carbon coatings.
An amorphous carbon coating is a structure including both sp2 and sp3 carbon-carbon bonds and has no clear crystalline structure (no grain boundaries). It features high hardness, high toughness, and low friction properties. Also, amorphous carbon coatings are considered to be superior to crystalline hard coatings such as TiN (titanium nitride) coatings and CrN (chromium nitride) coatings in terms of resistance to mechanical wear.
Some slide parts slide in contact with a seal member (make sliding contact with a seal member). When such a seal member is for sealing a fluid and is formed of an elastic body such as resin and rubber, in particular, the friction coefficient on the sliding surface (sliding contact surface) is generally high, and abrasion easily develops. Therefore, various techniques to improve durability (wear resistance) have been studied.
For example, JP-A 2003-185029 discloses a sliding structure, including a technique to form a DLC coating on a sliding contact region of a seal member which is in sliding contact with a slide part and generates a dynamic friction force. According to JP-A 2003-185029, it is possible to reduce wear (abrasion) in the seal member and in the slide part by taking advantage of the low friction properties of the DLC coating.
JP-A 2005-48801 discloses a sealed device, including a technique to form a hard carbon coating on a sliding contact surface of a seal member, or on sliding contact surfaces of both a seal member and a slide part, and to interpose a lubricant containing a specific friction modifier between the seal member and the slide part. According to JP-A 2005-48801, the sealed device exhibits high wear resistance and low frictional resistance.
JP-A 2009-169210 discloses an elastic roller for electrophotographic apparatuses, sides of the elastic roller being sealed by seal members, the elastic roller including a technique to form a DLC coating on sliding portions of the elastic roller in contact with the seal members. According to JP-A 2009-169210, the elastic roller exhibits both high sealing performance and high wear resistance.
JP-A 2006-189025 discloses a high-pressure plunger pump which sucks and discharges slurry containing atomized powder, the plunger pump including a technique to form a DLC coating on an outer peripheral surface of a plunger in the plunger pump in order to smooth the outer peripheral surface of the plunger and reduce the friction coefficient thereon. According to JP-A 2006-189025, it is possible to inhibit build-up of atomized powder on the outer peripheral surface of the plunger and improve the wear resistance of the plunger and a gasket.
JP-A 2004-137507 discloses a method for producing automotive parts, the method subjecting a surface of an automotive sealing component, the automotive sealing component being formed of rubber, resin, or the like, to a predetermined pretreatment and then forming a DLC coating thereon. According to JP-A 2004-137507, it is possible to provide automotive sealing components having good slidability on other articles, excellent in wear resistance and hardly deteriorating.
Meanwhile, various amorphous carbon coatings containing a ternary element that is neither carbon nor hydrogen have been proposed. For example, JP-A 2000-297373 discloses a sliding member used in a lubricant, the sliding member including a technique to form a surface layer of the slide member with at least a hard carbon coating, the hard carbon coating containing nitrogen and/or oxygen in the surface thereof. According to JP-A 2000-297373, the sliding member exhibits low friction properties and high wear resistance.
JP-A 2003-336542 discloses a slide member which slides in a presence of a lubricant, the slide member including a technique to cover a sliding surface of the slide member with a DLC coating containing silicon. According to JP-A 2003-336542, the slide member exhibits high wear resistance and high seizure resistance.
JP-A 2005-282668 discloses a connection jig entirely or partly covered with a hard coating of boron carbonitride having at least one of a diamond-like structure and a graphite-like structure. According to JP-A 2005-282668, it is possible to reduce the frictional resistance on a connection sliding surface of the connection jig.
However, in a conventional slide part/member in sliding contact with a seal member formed of an elastic body such as resin and rubber, the amorphous carbon coating thereof can wear more than expected due to the high friction coefficient on the sliding surface. In other words, conventional amorphous carbon coatings have poor durability (wear resistance) in slide parts in sliding contact with a seal member, and further improvements are required.